The present invention relates generally to electrostatic copiers, and more particularly to an electrostatic-copier cleaning device.
Electrostatic copiers known in the art have an endless travelling charge carrier, usually in form of a cylindrical drum, the surface of which can be electrostatically charged to form on it a latent image of an original to be copied. To the electrostatic charge on this surface toner particles are attracted to form an image which is thereupon transferred to an image carrier to form a copy of the original. Before the charge carrier can be re-charged for making the next copy, i.e., for the next operating cycle, residual toner particles which continue to adhere to the photosensitive surface of the carrier, must be removed.
For this purpose it is known in the art to provide cleaning stations in such electrostatic copiers. These cleaning stations usually employ rapidly rotating brush rollers, which may be of the bristle type or the type where the bristles are replaced by synthetic plastic foam material, or other devices used for removing residual toner particles from the charge carrier surface cause a substantial accumulation of the dust-like toner particles in the cleaning station. It is known to provide the cleaning arrangement in form of units which can be inserted into or removed from the housing of the electrostatic copier in toto. It has also been proposed to protect the remainder of the carrier against the toner dust that is removed at the cleaning station by constructing the cleaning units as a dust-tight cassette or cartridge with the purpose of preventing the escape of toner dust from the cartridge into the surrounding interior space of the electrostatic copier.
However, this prior-art proposal has been only partially successful, because the cartridge must of course have an open side which faces towards the photosensitive surface of the travelling charge carrier and at which the toner-removing cleaning instrumentalities, e.g., rotating brushes or the like, are located. In this region of the open side or end of the cartridge, therefore, dust continues to escape into the ambient interior spaced of the copying machine. Particularly, the two horizontal slots along the open end of the cartridge at the upper and lower edges bounding this end, i.e., the slots defined between these edges and the photosensitive surface of the charge carrier, have not heretofore been sealed at all, because no way could be conceived in which these slots could be properly sealed against the escape of toner dust on the one hand, without on the other hand damaging the highly scratch-sensitive surface of the charge carrier.